Here's a somewhat moderately broad stroke of my idea for what I would like to see Subaru come back with for the 20th Anniversary... Or just a new SVX GT coupe in general...
GR impreza chassis hard points. (basically the same thing as a BL Legacy, minus a bit of rear over-hang. the new Legacy/Outback platform is too big for Legacy, and SVX doesn't need to be that huge as a coupe.)
No aspect of Impreza's styling would be held over, though... The front end perhaps extended just slightly, an inch or as little as absolutely necessary, for Subaru's new low-front mount turbo engine, and to be sure an H6 option fits under the hood. Maybe re-fit for Subaru's new engine cradle, if it is worth including in the design.
BL LEgacy like low-cowl, low hoodline, and a mix of SVX and 2005-2007 Legacy GT front end styling. Minimal, non-embellished grille between the headlights, larger opening under the bumper beam.
SVX-like boxed, radiused fender flares, fitting 18x8 wheels, 5x114.3, capable of fitting 35-45mm positive offset wheels over brembo or Subaru-logo monoblock brakes, and bilstein USD dampers, similar to WRX STI.
SVX's flush fit glass canopy styling, including window-in-a-window and SVX's sleek fastback profile. IR and UV rejecting, visible-light-transparent film laminate in the windshield, and a similar coating applied to the rest of the glass as part of the factory glass tinting. the titanium coating is old tech...
Optional 2-panel glass roof, similar but larger than Scion tC or Mini, or louvered panel like was optional on Pontiac G6. Otherwise solid surface roof, possibly composite sheet over metal roof structure, to keep weight down. Roof rack attachment points on the rain rails above the door openings, similar to Porsche's integrated attachment system.
Liftback third door, similar to Ford Probe, which still had flush glass, and a bit of a horizontal profile change between the rear glass and the tail panel, but in this case styled closer to the original SVX's looks, with updated function: the dual-gate feature that SEAT and BMW and others have debuted... the back can open like a trunk, or fully open to the roof, like a hatch.
Fold flat split rear seats, and a fold-forward-flat passenger seat, for the very occasional ability to carry long cargo from the passenger's footwell all the way back to the trunk. power actuated from the trunk, as part of the passenger seat's power adjustments, and a solenoid release for the rear seat backs. (another trigger button for the rear seat backs being just inside the front passenger doors, to fold the seats from there, too.
Front seat mounted safety belts... All the convenience of getting to the rear seat area without a seatbelt in the way, and none of the hassle of 92-94 SVX's automatic belts, with separate lap belts. Standard 6 airbags. Heated and cooled seats, cloth or perforated leather, full power adjustment, and driver's side memory settings tied to mirrors and other pre-sets.
Full LED lighting for the whole car, from tail lights to illuminated interior buttons, to front turn signals. Electro-luminescent, LCD, or OLED gauges and information displays.
~6000K HID low beams, HIR 9011 high beams, optically focused LED amber/white fog lights, and white running and reverse lights.
Either traditional side mirrors with heated glass, LED indicators visible from lateral front and rear quarters, and auto-downtilt in reverse, and electric folding retraction... OR the first production car with CCD camera based side view 'mirrors', in order to cut down aerodynamic drag. Possibly shown on the LCD-based gauge display panel for the driver. Rear-view reverse and parking cameras, possibly 360-view of the ground around the car on the NAV screen, like new Infinitis are equipped with.
Multi-color Heads-up-display in the windshield, with adaptive display programming to bring pertinent information to driver's attention faster, in the driver's heads-up line of sight, possibly reducing the amount of information required to simultaneously display on the dash... But considering the digital display nature, such settings can be tailored to the driver's preference.
Personal bluetooth driven keyless entry and start (manual-gearbox models not getting remote start, just keyless start), which also triggers seat and mirror position memory, and information system preferences.
ICE/NAV screen in the dash with multi-touch, oleophobic touch screen tech, similar to new iPhone screens, but most direct functions driven by haptic physical buttons. (changing to radio controls, vs NAV controls, and what not... things that should be more inherent than being stuck in menus) HVAC run separately by Tribeca's 3 LCD-integral dials, not by ICE/NAV display.
Drivetrain:
2.0-2.5 liter H4 base engine, updated with DOHC, AVCS, and direct fuel injection for effective efficiency.
3.2-3.6 liter H6 main-line engine. EZ36R, maybe EZ32R if the engine can be made more robust by pulling back on the stroke length, and fitting normal rods, rather than the 3.6's asymmetrical con-rods. Similarly DOHC and DFI, with AVCS-II, a variable valve event and lift system similar to Nissan's VVEL system, or BMW's Valvetronic valve control system, or even corporate-partner Toyota's Valvematic system, which can control lift, as well as timing. 330+ horsepower target, perhaps on lower octane fuel.
Special edition "STI" model: twin-scroll 2.5-2.8 EJ engine, similar to '10 Legacy's low-front mount turbo, but tuned to STI specs or better, with a front-mount intercooler, and an offset-front intake manifold, like a rotated 05+ Legacy or 08+ WRX intake...
gearboxes:
base engine gets WRX 5MT or the Legacy/OB/Tribeca 5EAT-sport-shift/VTD. Viscous rear limited slip.
H6 and STI H4T get WRX STI-sourced 6MT DCCD/VTD front and rear torsen LSD setup, similar to WRX STI S204
or a new dual-clutch automated gearbox, like PDK/DSG, and the systems that Nissan GT-R and EVO X use.
The 5 and 6MT models would get a standard linkage-operated shifter, and clutch pedal.
The 5EAT and dual-clutch automated gearboxes would be electronically controlled from the dash, no shift lever needed. Maybe some sort of slick knob selector like the Jag XF has...
SI-Drive-II or plus, or something... next generation. not only does it sharpen throttle response and adjust fuel maps... it also adjust shift profiles on the automatic and dual-clutch gearboxes (think SVX Power Mode, and sport-shift as manual-mode, with shift paddles on the steering column, and the dual-clutch being much faster, and as direct-connected as a manual gearbox
)
It would also adjust the profiles of the Variable torque distribution of the center diff on all gearboxes, except the base 5MT, and adjust the VDC and ABS engagement thresholds, or defeat them almost entirely.
It would also control the bilstein PSS10/B16 adjustable dampers, possibly magneto-rheological fluid dampers that some cars are using, as well as the electro-hydraulic power steering assist profiles, while both still being road-speed sensitive. Tied to 4-wheel active steering, if so equipped... (also optional on G37 now.)
SI-Drive would become somewhat like F430's Manettino switch, but tied into most of the dynamic systems on the car.
I'd love to see a way to connect a PC/Mac/iPhone with a stand-alone configuration application to go through the car's configurable control and display systems, and set them to your preference, within a factory defined range, including things like door handle pull-code keyless unlocking, if you lock your keys in the car... visual dash representation "skin" options, and how much information is displayed standard, vs how much comes up as an alert if something meets alarm criteria. All that stuff would be tied to a profile, including seat and mirror memory positions, and perhaps directly to a bluetooth or encrypted RFID keyless entry identifier, if each one is unique. (It would be able to tell between you or your spouses identifier, and adjust the car's settings accordingly, including moving the seat before you even sit down.)
Personally, I would also like to see butterfly hinged doors, to try to minimize the parking space width the car requires to open long coupe doors, to allow people to get into the car. Theoretically, that could be another argument for a liftback hatch, and trunk-triggered folding seats... as it would be easier to crawl into the car and pull it out of the parking space, if people park too close for you to open the side doors wide enough to slip through. Long coupe doors require wider side clearances, but when the clearances are there, they are nicer to get in and out of than shorter doors on multi-side-door vehicles.